In order to raise aquatic animals which are by nature carnivorous and thus require separation during growth, it is important not only to separate the animals, but also to provide a system in which the animals can be properly cared for, provided with adequate food, and provided with fresh water and air on an efficient basis. Crustaceans and more particularly, lobsters, are difficult to raise in captivity due to a number of problems mainly related to the cost of the rearing and the health of the animals which obviously impacts on yield.
It will be appreciated that lobsters and most crustaceans are very delicate animals to rear, mainly because of bacteriologic infections such as gafkemia. Gafkemia invades the bloodstream via wounds which the animals may suffer as a result of attacks by other animals or as a result of handling. Moreover, infection can be aggravated by inadequately cleaned habitats and the non-availability of fresh air and water. Contaminated water or water not in sufficient supply and not sufficiently aerated will cause an early demise to a large portion of the animal population when raised intensively in habitats. Additionally, with each incident of direct contact handling, the animals are subjected to stress and trauma which can directly kill the animals, impair their growth, or encourage other infections.
Thus, it is desirable to provide an improved animal rearing habitat and system which minimizes the direct handling of the animals, does not subject them to trauma, provides adequate water management and quality and in general, provides an efficient system for the rearing of the animals.
In the past, there have been numerous systems for rearing crustaceans which systems either raise the animals in cages in their natural sea habitats or provide tanks for the rearing of these animals such as that described in U.S. Pat. No. 3,815,546 issued to Emile A. P. Plante on June 11, 1974.
As the rearing of animals in their natural environment, it will be appreciated that the majority of the systems which utilize cages utilize them in a lobster pound which freezes over in the winter. Thus, there is little or no accessibility to the animals within the pound during a large portion of the year. Typically, the success of such an operation also depends on the absence of disease, it being understood that once a diseased animal is present, he may infect the rest of the animals within the pound, and thus all or many of the animals in the pound may be lost, especially in winter when they are inaccessible because of ice and can't be serviced.
With respect to the Plante type habitat, it will be appreciated that the habitat compartments are formed by the cooperation of shelves or discs with the inner wall of the tank. While this is satisfactory in some aspects, it will be appreciated that if the disc assembly is withdrawn to remove an animal, all the animals fall off the discs, and thus must all be individually handled to access only one animal. Moreover, there may be contamination of these habitats by virtue of bacteria in the air which settles on the surface of the water at the top of each tank. This generally causes an annular ring of algal growth within the tank which attracts bacteria and presents a severe health problem.
It will be appreciated, from the Plante patent, that the base is either welded or adhesively attached to the cylindrical tank which results in stress corrosion of the super adjacent surfaces, and early material failure resulting in leakage and other maintenance problems. Moreover, because of the flat bottom, cleaning of the tank is impossible without removing the animals. Additionally, the tank walls must be made exceedingly thick in order to be able to accommodate the welding and bonding operations.
In general, tank type aquaculture systems require manual handling of animals during cleaning operations, animal, transfer, or animal removal. Moreover, animal health is ascertained by inspection of each animal after it has been removed from its habitat. Additionally, the animals, when transferred are, in general, kept in a water bath to keep them alive. This requires a tremendous amount of space and handling which, in general, is awkward, costly and detrimental to the animals' health.
In the subject system, a novel type of habitat is utilized in which nested baskets take the place of the animal rearing chambers of the Plante patent. Moreover, they are removably attached to a strongback fixture which maintains the baskets in their stacked arrangement either within the tank or during overhead transit. The removal of the animals is thus quickly and efficiently done without damage to, or handling of animals not involved in the transfer.
The basket structure is such that for large animals, the basket is undivided, with one basket on the top of another basket forming a top to keep the animal in the next immediate lower basket in place. Food is delivered through the strongback member by apertures therethrough which expose a feed rod which has compartments containing food. When the feed rod is in place, the apertures in the feed rod are in alignment with the apertures in the strongback member and also an aperture in the wall of the basket such that the animal may have access to the food in the feed rod. There is sufficient "draft" to the basket to allow easy attachment or removal from the strongback. For smaller animals, so-called "half baskets" are provided which are nestable and are provided with a shelf-like structure which permit twice as many animals access to a single feed rod thereby minimizing the space of rearing of animals of a predetermined size. For even smaller animals, this shelf containing half basket is further subdivided by a simple divider so that two animals can be raised in each half basket.
The tanks in general are modular in nature and have a tripod-type foot which permits a staggered arrangement of the tanks for easy visibility and animal surveillance. Each tank is made of a thin-walled cylinder with top and bottom circumferential restraint. The wall thickness is thus only that which is necessary to restrain the water column in hoop stress. The bottom of the tank is press fit into a frusto conical type tapered base member which contains a flushing valve for the removal of detritis and cleaning of the tank. This flushing system is designed to remove heavy sedimentary waste material. For lighter particulate matter, this matter is carried upwardly by the upward action of air lift circulation due to aerator bubbles which move upwardly and expand in their travel towards the top of the tank where they are carried away by the skimmer. Water flow is also in an upward direction. A skimmer which completely surrounds the top of the tank is employed so as to remove the light particulate matter. The skimmer, by virtue of its surrounding the entire top of the tank, prevents airborne bacteria and other contaminants from entering the tank which is a major factor in the prevention of disease.
An overhead conveyor type transfer system is utilized when either the feed rods are removed for replenishment or animals are loaded or harvested. When the animals are removed from the tank by virture of the raising of the strongback member, a fog chamber is provided to maintain moist gill surfaces so that the animals do not suffocate during their travel from one position to another in this production system. It is a finding of this invention that moist air or fog is sufficient to keep the animals alive for long periods of time and thus, the animals need not be immersed in water during transfer.
Additionally, animal health and growth is monitored by ascertaining the amount of food eaten by each lobster each day. The amount of uneaten food remaining in the feed rod is measured and indicates the relative health and/or growth of the animal. In one embodiment, a fixed scanner is utilized to scan the feed rods as they pass the scanning head prior to their being replenished. The amount of food left is correlated with the particular feed rod, tank, and compartment, and therefore, a particular animal. In this manner, the size, weight and physical condition of the animals may be monitored without physically removing them from the habitat or without attempting to measure them by visual inspection through the transparent tank walls. Thus, a constant watch can be kept on all of the animals to prevent disease, and in general, to monitor growth of the animals.
What has been solved by the utilization of this improved animal rearing system is the provision of a material handling system which is efficient and which does not subject the animals to undue stress. Moreover, water quality is easily maintained and animal separation is insured by use of the basketlike structure. Modularity of the tanks and their mounting system provides an unusually dense but flexible configuration for the rearing of the animals as well as visibility of all of the animals within the habitats. The above system increases serviceability and efficiently provides for any mix of animals of different sizes. This enables operation at 100% capacity at all times.
It is therefore an object of this invention to provide an improved aquaculture rearing system;
It is another object of this invention to provide an improved habitat design and materials handling system for the efficient raising of aquatic animals;
It is yet another object of this inventon to provide an improved animal monitoring system in which the health and size of the animals are monitored indirectly by monitoring the amount of food consumed in a given time period;
it is a still further object of this invention to provide for the safe transit of animals by the utilization of a fogging system in which the fog surrounds the animals during transit and promotes respiration.
These and other objects will be better understood in light of the following specification taken in conjunction with the dependent drawings wherein: